1. Field of the Invention
This invention relates to a cleaning, descaling and corrosion inhibiting composition and a process for employing same.
2. Description of the Prior Art
Equipment used in power plants, chemical and petrochemical plants, paper mills, sugar mills, pipelines, air conditioners in large buildings and many other industrial environments are subject to the formation of scale, either by circulating water or by process compounds. This includes all types of heat exchangers, boilers, vessels, piping and other equipment. Precipated solids reduce the heat transfer efficiency and oftentimes cause tube failure due to overheating which may result in plugging or fouling of the equipment. To prevent interference with industrial processes, cleaning of the metal surfaces of the equipment employed therein is required. The water-formed precipitates are generally inorganic in nature, especially precipitates formed in hot closed systems, for example, in steam generators or heat exchangers. Common deposits which are found include iron oxides (magnetite and hematite), sulfides, alkaline earth carbonates, sulfates, and silicates.
Hydrochloric acid is widely used for the chemical cleaning of structural steel from which heat transfer and piping systems are fabricated. Hydrochloric acid forms soluble products which serve to dissolve calcium or magnesium carbonates. Hydrochloric acid, does not, however, dissolve sulfates or silicates. Therefore, other chemicals must be mixed or incorporated with the hydrochloric acid. It is also well known that hydrochloric acid is highly corrosive. In addition, if copper salts are present in the scale, they will dissolve and reprecipitate on iron surfaces causing severe localized corrosion.
It is an object of the present invention to provide a non-toxic, industrial descaling and cleaning composition which is effective in removing scales and oxides from the surfaces of the process equipment used in various industries while avoiding corrosion to the equipment.